Operating Systems – Introduction Slide 1

Operating Systems

Rafael Ramirez (T, S)

rafael.ramirez@upf.edu 55.316

Sergio Giraldo(P, S)

sergio.giraldo@upf.edu Matteo Segnorini (P, S)

matteo.segnorini@upf.edu

T=Teoria; S=Seminarios; P=Prácticas

Operating Systems – Introduction Slide 2

Operating Systems

Calendario Curso en: Ø Web de la ESUP

Operating Systems – Introduction Slide 3

Operating Systems Topics: 1. Operating System introduction 

- Introduction, operating system components, types of systems, …   2. Process Management - Processes & threads, process synchronization, CPU scheduling, …   3. Memory Management - Main Memory, virtual memory   4. Storage Management - File-system interface, file-system implementation   5. I/O systems & security - I/O hardware, application I/O interface, security threats

Operating Systems – Introduction Slide 4

Operating Systems Evaluation: Examen teoría 60% Prácticas 30% se ha de aprobar tanto teoria como prác/sem

Seminarios 10% Prácticas = (0.6 * practicas) + (0.4 * examen de prácticas)

se ha de aprobar tanto prac-examen como prácticas

Participación

Operating Systems – Introduction Slide 5

Operating Systems

Operating Systems – Introduction Slide 6

Operating Systems

Seminarios (4): grupos de 2-4

Prácticas (5): grupos de 2

Operating Systems – Introduction Slide 7

Operating Systems

Course Book: A. Silberschatz, P.B. Galvin, G. Gagne. Fundamentos de sistemas operativos. McGraw Hill, 2009. Other books: W. Stallings. Sistemas operativos : aspectos internos y principios de diseño, Prentice Hall 2005.  

L. Duran-Rodriguez. Sistemas operativos: referencia bàsica. Marcombo, 2000.   A.S. Tanenbaum, Modern operating systems. Prentice Hall, 2001.

Operating Systems – Introduction Slide 8

Operating Systems

Contact: q  Clase q  Seminarios/Prácticas q  Email q  Horas oficina: Cualquier dia (previa cita) q  Anuncios, documentacion, … q  Moodle + http://www.dtic.upf.edu/~rramirez/os/

OS Introduction Slide 9

Introduction

Chapter 1 & 2 - Course Book

OS Introduction Slide 10

What is an Operating System?

OS Introduction Slide 11

What is an OS?

OS Introduction Slide 12

What is an Operating System?

"   A program that acts as an intermediary between a user of a computer and the computer hardware.

"   Operating system goals: l  Execute user programs and make solving user

problems easier. l  Make the computer system convenient to use.

"   Use the computer hardware in an efficient manner.

OS Introduction Slide 13

Types of Operating Systems?

"   OS for Batch systems "   Time-shared OS (multiprogramming)

l  Why multiprogramming? l  OS features needed for multiprogramming?

"   Desktop OS – convenience/responsiveness? "   OS for Parallel systems

l  Tightly coupled system l  Throughput? Economy? Reliability? l  Symmetric/asymmetric multiprocessing?

OS Introduction Slide 14

Types of Operating Systems?

"   OS for Distributed systems l  Loosely coupled system – LAN & WAN

"   Real-time OS l  time constraints l  Soft real-time l  Hard real-time

"   Hand-held OS l  Limitations

OS Structures Slide 15

Common System Components A system as large and complex as an OS can

be created only by partitioning it into smaller pieces

"   Process Management "   Main Memory Management "   Secondary Storage Management "   File Management "   I/O System Management "   Protection System "   …

OS Structures Slide 16

System Calls "   System calls provide the interface between a running program and

the operating system. l  For example – open input file, create output file, print message

to console, terminate with error or normally l  Generally available as routines written in C and C++

"   Mostly accessed by programs via a high-level Application Program Interface (API) rather than direct system call use l  Provides portability (underlying hardware handled by OS) l  Hides the detail from the programmer

"   Win32 API for Windows "   POSIX API for UNIX, Linux, and Mac OS X "   Java API for the Java virtual machine (JVM)

OS Structures Slide 17

API – System Call – OS Relationship

OS Structures Slide 18

Standard C Library Example "   C program invoking printf() library call, which calls

write() system call

OS Structures Slide 19

System Call Parameter Passing "   Three general methods used to pass parameters to the

OS l  Simplest: pass the parameters in registers?

l  Parameters stored in a block, or table, in memory, and address of block passed as a parameter in a register

l  Parameters placed, or pushed, onto the stack by the program and popped off the stack by the operating system

OS Structures Slide 20

OS Design Implementation "   Mechanisms determine how to do something, policies

decide what will be done. "   The separation of policy from mechanism is a very

important principle in designing OSs l  It allows maximum flexibility if policy decisions are to be

changed later. l  The timer is a mechanism providing CPU protection. How

long it runs for a particular user is a policy decision.

OS Structures Slide 21

Virtual Machines

Non-virtual Machine" Virtual Machine"•  appearance that users have their own processor •  operator’s console? Virtual computer/memory?

OS Structures Slide 22

Communication Models "   Communication between processes may take place

using either message passing or shared memory. "   Message passing

l  Information is exchanged through an interprocess communication facility provided by the OS

l  Computers have host names, processes have process names for identification purposes

l  Useful when smaller number of data need to be exchanged l  Easier to implement than shared memory

"   Shared memory l  Processes use map memory system calls to gain access to

regions of memory owned by other processes l  Allows maximum speed and convenience of

communication l  Problems arise in the area of protection and synchronization

OS Structures Slide 23

Communication Models

Message Passing" Shared Memory"